Many applications require redirecting small volumes of fluid flow. For example, valved conduit systems are widely used for high pressure chemical processing, fluid injection systems, aerosol delivery, or gaseous fluid bed object support systems. The high velocity fluid flow may be internal (for example, a switching conduit system), or external (for example, a turbulence reduction system requiring opening or closure of microflaps in an airplane wing or body).
Traditionally, low power control of such systems is difficult because of the significant energy required to counter or redirect the flow during valve closure. Powerful electromagnetic or unwieldly mechanical systems were required to quickly redirect swiftly flowing air, water, or other fluid. Low power electrostatic valving systems, while often adequate for low velocity valving applications, were not sufficiently powerful for use in conjunction with certain flow regimes.
The present invention circumvents the high power requirements for directly opposing fluid flow by providing a low cost and practical mechanism for capturing a portion of the energy of the fluid flow, allowing consistent and reliable redirection of fluid flow. While still allowing the use of electromagnetic or mechanical valve control, the present invention advantageously allows for the use of low power electrostatic or electromagnetic control. The present invention includes a valve for redirecting fluid flow having a valve chamber supporting fluid flow, with the valve chamber having an inlet, a first outlet, and a second outlet. The valve chamber can be closed (e.g., a pipeline flow diverter or manifold) or partially open (e.g. for external applications such as airflow diversion on an airplane's wing). The flap element supported (by a flap support) at least partially in the valve chamber has a first and a second end, with the first end attached to the flap support and the second end extending into the valve chamber. The flap element is movable to alternatively block the first outlet and the second outlet (or additional outlets if present).
In or immediately adjacent to the valve chamber are opposing first and a second catch mechanisms for controllably latching the flap element to block respectively the first outlet and the second outlet. The first and second catch mechanisms respectively have a disabled state and an activated state for holding and allowing release of the flap element. Once the first or second catch mechanism is disabled, the flap element is free to move to another position. The present invention provides an impulse mechanism for kicking the flap element into the valve chamber away from one of the first and second catch mechanisms after one of the first and second catch mechanisms is controllably brought into the disabled state. Since the flap element is unstable when unlatched during typical fluid flow conditions, oscillations of the flap element in the fluid flow will eventually bring the flap element into catchment range of one of the first and second catch mechanisms in an activated state. The impulse mechanism can arise from Bermoulli forces exerted on a flexible flap element that induce fluttering oscillations lifting the flap, or can include mechanical, electromechanical, or electromagnetic forces such as may be applied by electrically activated shape memory metals, piezoreactive ceramics, or magnetic materials.
The catch mechanism can include a first electrostatic plate separated from the flap element by a first dielectric, with an electric charging unit connected to at least one of the flap element and the electrostatic plate to apply a voltage differential for electrostatically attracting and holding the flap element to block the first outlet in the activated state. Alternatively, an electromagnet attached to either (or both) the valve chamber or the flap element to electromagnetically hold the flap element to block the first outlet in the activated state can be used, as can a releasable electromechanical latch attached to either (or both) of the valve chamber and the flap element to mechanically hold the flap element to block the first outlet in the activated state, and allow disengagement when disabled.
In certain embodiments the flap element is substantially flexible along its length. Such a flexible flap element can be attached to the flap support like a reed of a musical instrument so that it trails (with respect to oncoming fluid flow) the second end extending into the valve chamber. Alternatively, the second end extending into the valve chamber can be arranged to trail the first end attached to the flap support, so that it flutters like a flag with respect to oncoming fluid flow.
In one particularly favored embodiment, the flap element is attached to the flap support. The flap element also has a hinged flap, vane, rudder, or other projectible element attached to it by a hinge joint, with the hinged flap being movable into fluid flow by the impulse mechanism. Once even slightly raised into the fluid flow, the hinged flap utilizes the energy of the fluid flow to further raise itself into the fluid flow, eventually leading to capture by the opposing catch mechanism (and rediversion of the fluid flow).
Since the present invention relies on the use of an unstable closure element (such as the foregoing flexible flap element) to redirect fluid flow in two or more directions, it can be very power efficient, with very small initial forces being amplified by the fluid flow into large movements of the flap element. As will be appreciated, with suitable modifications, valves in accordance with the present invention can use substantially flat flap elements, projecting flaps or vanes, three dimensional (e.g. airfoil geometries), cylindrically mounted flaps, screws, rotary vanes, or any other suitable shape suitable for controllably redirecting air flow. As will be apparent from consideration of the present disclosure, redirection of fluid doesn't even require closed conduits or chambers, but may be practiced in conjunction with partially open chambers having flaps extendible into external air flows over airplane wings or other structures exposed to high velocity fluid flows.
A particularly preferred embodiment of the present invention provides for valves embedded or attached immediately adjacent to conduits, passageways, or apertures defined in or supported by the laminate. Large scale arrays of valves for controlling fluid flow can be easily connected to centralized or distributed controllers by the photolithographically formed metallic electrical connections. In conjunction with appropriate sensors and fluid pressure sources, these arrays can be used to precisely control fluid flow, for dynamic control of fluid instabilities, for supporting movable objects such as paper, or for injecting electrical charge, dyes, inks, or chemicals into chambers or conduit systems.
As will be appreciated by those skilled in the art, large arrays of valves in accordance with the present invention have particular utility in conjunction with an object transport device or other material processing system that must precisely control position and velocity of paper or other objects moving through the system. Such a system is disclosed, for example, in U.S. Pat. No. 5,634,636, assigned to Xerox Corp., the disclosure of which is hereby expressly incorporated by reference. While the use of air jet mechanisms for support of solid objects is generally straightforward, accurately supporting flexible objects such as continuous rolls of paper, sheets of paper, extruded plastics, metallic foils, wires, or optical fibers is much more difficult. In such systems, the flexure modes can result in complex object behavior that may require constant high speed switching of numerous valved high velocity air jets. Unlike rigid objects, flexible objects are dynamically unstable when supported by air jets, with edge curl, flutter, or other undesirable dynamic movements continuously occurring during support and transport. Such undesirable movements of the flexible object can result in mispositioning, transport failure, or even damaging surface contact between the flexible object and an air jet conveyor.
Accordingly, the present invention provides novel valve structures for use in a fluid transport apparatus. The valves of the present invention can effectively work with either continuous or discrete flexible objects moving through a materials processing system. In a most preferred embodiment of the present invention, paper or other graphically markable material is among the flexible objects capable of being controlled by an array of unstable flap valves in accordance with the present invention. A paper handling system includes a plurality of valved air jets adjusted for transport of paper, with at least a portion of the plurality of air jets being individually controllable. A sensing array continuously (or intermittently) determines paper position, and an air jet control unit connected to the sensing array is configured to modify paper trajectory in response to information received from the sensing array. In response to the calculated position, the air jet control unit modifies paper movement or orientation (for example, by selectively increasing or decreasing air flow from air jets that impart momentum to defined subregions of the paper) to nearly instantaneously correct for discrepancies in the motion state of the paper, including its position, orientation, trajectory, velocity, flexure, or curvature. In preferred embodiments, the plurality of valved air jets can be used to apply tensile or compressive forces to flatten paper, and the air jet control unit can be used to maintain paper in this flattened position during transport. Of course, other paper positions (in addition to flat) can also be maintained, with, for example, the plurality of opposed air jets being used to generate sufficient force to curve selected subregions of the paper.
Additional functions, objects, advantages, and features of the present invention will become apparent from consideration of the following description and drawings of preferred embodiments.